Currently, network signalling (NS) techniques are being investigated to improve carrier aggregation (CA) operations by the 3rd Generation Partnership Project (3GPP) in the Technical Specification Group Radio Access Network No. 4 (TSG RAN4) to support the progression of Long Term Evolution Advanced (LTE-Advanced or LTE-A) and beyond (LTE-B). Carrier aggregation allows an evolved Node B (eNodeB) to group several distinct carrier channels into one logical channel to provide enhanced wider transmission bandwidths over prior releases which were limited to transmission over a single 20 MHz channel. Each aggregated carrier is referred to as a component carrier (CC) which can have a bandwidth of 1.4, 3, 5, 10, 15 or 20 MHz. CA can support up to five 20 MHz component carriers (CCs) to achieve high-bandwidth transmission, such as peak data rates of 1 Gbps in downlink (DL) reception and 500 Mbps in uplink (UL) transmission.
There are multiple configurations possible with CA which are generally described in three different spectrum scenarios: intraband contiguous CA, intraband non-contiguous CA and interband (non-contiguous) CA. Intraband contiguous CA and Intraband non-contiguous CA aggregates CCs in the same operating band. Contiguous carriers are defined as two or more carriers configured in a spectrum block where there are no radio frequency (RF) requirements based on co-existence for un-coordinated operation within the spectrum block. Interband (non-contiguous) CA aggregates CCs in different operating bands.
Multiple-band operations such as interband non-contiguous CA can also aggregate both UL/DL CCs in both frequency division duplex (FDD) and time division duplex (TDD) operations. In FDD operations, the number of aggregated carriers can be different in DLs and ULs with the caveat that the number of UL component carriers is often equal to or lower than the number of DL CCs. Moreover, the individual component carriers can also be of different bandwidths. In TDD operations, the number of CCs and the bandwidth of each CC may be the same for DL and UL. Alternatively, TDD operations may allow for an unequal number of CCs.
However, aggregating multiple operating bands among UL/DL CCs in mixed FDD and TDD CA is not currently possible.
The following abbreviations which may be found in the specification and/or the drawing figures are defined as follows:
3GPP 3rd Generation Partnership Project
A-MPR additional maximum power reduction
AP Access Point
CA carrier aggregation
CC component carrier
D-AMPR dynamic additional maximum power reduction
DB dual-band
DC dual-carrier
DL downlink
eNode B evolved Node B
E-UTRAN Evolved Universal Terrestrial Radio Access Network
FDD frequency division duplex
FE front-end
GLONASS Globalnaya Navigatsionnaya Sputnikovaya Sistema
GNSS global navigation satellite system
GPS global positioning system
LTE Long Term Evolution
LTE-A Long Term Evolution-Advanced
LTE-B Long Term Evolution-Beyond
NS network signalling
OOB out-of-band emissions
PSD power spectral density
TDD time division duplex
UE user equipment
UL uplink